The second series of The Killing(BBC4, Saturday) would always have to bear the weight of expectation created by the first. And yet it seems unfair to judge its worth against the backdrop of a phenomenon that ended up leaking all over the cultural landscape: it made ugly jumpers fashionable, Danish design cool and actor Sofie Gråbøl an international star. If only we could ignore the first series completely, and start afresh with the second. But where on earth would you find a TV reviewer who hadn't seen The Killing?

Ahem. That's right. Not a single episode. Nope, not even from the American remake. I wasn't holding a grudge against The Killing just because it was popular (although frankly I'm not above that sort of thing); it's just that at some point I gave up on the idea of catching up and added the first series to the bottom of a long list of box sets I am never going to buy.

So, let's begin – the slate is blank. Season 2 starts with a 999 call – that's 112 in Denmark, if you ever get in trouble there. The man sounds incredibly distressed, and if anything it sounds worse in Danish. The body of a woman turns up in a park, and her estranged husband is located not far away, covered in blood. Case closed, you would think.

Sarah Lund, meanwhile, has been busted down to policing ferry traffic. I gather things didn't end so well for her last time. A visiting cop labouring under the name of Ulrik Strange wants her to take a look at the park killing – something doesn't add up – but she refuses. She doesn't get involved with the victim-and-perpetrator end of things any more. Then she goes home and puts on this horrible red jumper and ... Oh God, I'm hooked.

Why didn't I jump on this bandwagon sooner? What was I waiting for, an invitation? Two episodes in and I'm already beginning to exhibit symptoms of abject fandom, including the delusion that I have at some level been able to speak Danish all along.

Describing its virtues to the initiated will be, I imagine, irritating, but allow me the zeal of a late convert. As a police procedural The Killing is grimly efficient and sporadically gruesome. As a melodrama it's extraordinarily spare, and as a tour of Danish soft furnishings it's an education. Yes, the cinematography is moody enough to give one Seasonal Affective Disorder, but this would explain why everyone has killing on their minds. There is a timely political subplot, although I would suggest that to distinguish between plot and subplot at this stage may ultimately prove unprofitable. Everything is connected.

As a protagonist, Lund is an innovation – reluctant, unassuming and partly broken, with nothing but a sharp eye and a covert tenacity to sustain her. Her miserable personal life is deftly sketched in, but no less affecting for it – when Lund goes to her own son's birthday party she has to apologise for the size of the hoodie she bought him – it's clear she doesn't see him enough to know how much he's grown.

Much of its appeal, of course, is down to the foreign setting. It makes the whole thing that much more unsettling, because you can't tell whether a character is behaving oddly, or whether he's just being Danish. And thanks to that grim Danish half-light, one spends the whole time peering warily into the murk, looking for clues and cool lamps.

One spoiler: the title's a bit of a misnomer this time out, because two people die in the first episode. It should really be called The Killings.

We're not used to hearing good news about medical survival rates, and in Frontline Medicine (BBC2, Sunday) the statistics come packaged in a tragic context. The good news is that in one British hospital they're keeping 90% of their casualty admissions alive. The bad news is it's the Camp Bastion hospital in Helmand province, Afghanistan. We're not quite as good at keeping soldiers alive as we are at sending them out to be killed, but the gap is narrowing.

Presenter Michael Mosley travelled to Helmand to see how they're treating once routinely fatal injuries with remarkable success. Their number one problem is massive blood loss, and their number one solution is putting it back. "We use blood products aggressively," said one doctor. He's not lying – in the period between injury and surgery, it's not unheard of to replace a soldier's entire blood supply five times over. Some of the innovations developed in Afghanistan are now cropping up in the NHS, but again, it's hard to consider this unalloyed good news.